19 votes
Accepted

For electricity use, which is better: Turning all appliances on at the same time, or spread out?

The "surge" that the electric utility was referring to is the demand charge: The kWh charge (consumption) is the measurement of the amount of energy the building uses over the given period ...
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  • 11.2k
14 votes

Which solar power technology has the highest energy return on investment (EROI aka EROEI)?

TLDR; cadmium telluride panels have the highest EROI of the mentioned PV panels (around 34.2) EROI estimates vary widely. This is because of differences in the method of calculation, scope of the ...
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  • 14k
13 votes

What form of electrical lighting has the smallest energy-footprint?

i signed up just so i could make this comment. THelper♦ provided a good link to a DOE report on this topic, which i was researching because my roommate is skeptical about the advantages of efficient ...
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  • 231
13 votes

Are fuel cell electricity generators a sustainable way of making electricity?

No. There is no readily available supply of net-positive-energy hydrogen on Earth, where most human power usage takes place. Hydrogen fuel cells may be a useful component of a total energy system ...
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12 votes
Accepted

Do switchable sockets left "on" use electricity if there's nothing plugged in?

No. With nothing plugged in there is no circuit, so no current can flow. An exception to this is if the socket or the switch has an indicator light - usually a neon one - that is illuminated when ...
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  • 3,601
11 votes
Accepted

Transmit solar over multiple time-zones?

Yes, we can. Estimates vary of the losses in long-distance HVDC (high-voltage direct current) transmission, but they're around 3-4% per 1000 km. Now, those operate at far higher voltages than you've ...
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  • 14.6k
11 votes

Getting power from an innovative new mechanism

No, you cannot get more energy out than you put in. No, you cannot invent a perpetual motion machine.
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  • 14.6k
10 votes
Accepted

Is electricity used at night more likely to be renewable?

In Ireland, electricity is equally likely to be from renewable sources during the day as during the night ENTSO-E, the European Network of Transmission System Operators for Electricity, provides a ...
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  • 11.2k
9 votes
Accepted

Which types of spare electric motors from common consumer appliances are suitable to repurpose as generators?

DC motors: The most suitable motors are those which have permanent magnets in their rotors. Traditionally these were pure DC motors - where DC was fed into the motor rather than AC such as is ...
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9 votes

How much power does a computer monitor left switched on use?

Usually its around .5-10 Watts depending on the make/model/size etc. I would recommend getting a kill-a-watt meter and checking a variety of monitors to get a rough idea of the average. Then you could ...
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  • 195
9 votes

How worthwhile is it to use energy during daylight to take advantage of grid-based solar power?

In the purist sense of "the electricity I use was actually generated by a wind farm", your idea is broadly correct. However, unless you actually have solar panels or a wind turbine on your house, that'...
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  • 3,755
8 votes

How worthwhile is it to use energy during daylight to take advantage of grid-based solar power?

You're being quite specific with regard to solar... but in principle, it is possible to move your electricity consumption to minimise its carbon footprint. Ecotricity (a UK "green" energy supplier) ...
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  • 3,601
8 votes

How can I manage my fridge's contents better?

I think Western kitchens have a much different focus on foods, as well. Meat is often the center of many meals, for instance. I find efficiently storing (freezing, thawing, cooking, storing prepared ...
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8 votes

Hydro-electric generation from roof-collected rainwater

If it's a very simple motor then it may be possible just to run it backwards to generate electricity. If it's got electronic controls, probably not. But is it worth it? Do a quick calculation of the ...
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  • 14.6k
8 votes

Do USB outlets waste energy just like conventional wall warts?

Electronically they're the same and will waste as much energy as a conventional adaptor. Depending on your electrical regulations they may be forced to be at the good end of adaptor efficiency, or ...
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  • 2,037
8 votes
Accepted

Can 140 square miles of solar panels power the US?

Summary No, that's way too little. I think "140 miles square" has got mangled into "140 square miles". Running the numbers Following on from one of Elon Musk's presentations, which ...
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  • 14.6k
8 votes
Accepted

How much energy would it cost to stabilize 2 tons of water at 70 degrees?

The stabilisation energy rate will be exactly exactly equal to the rate at which energy is lost. Assuming the tank is closed, so there are no evaporative losses, there are two other ways energy is ...
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  • 14.6k
8 votes

How to ensure you are using efficient chargers for cell phones, laptop computers, and other electronic devices?

Power ratings -- choose level VI Take a look at any external power supply (EPS) you have lying around -- you should notice, along with all the regulatory markings, a roman numeral I through VI in a ...
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  • 11.2k
7 votes

What is the number 1 country by global installed wind capacity: the United States or China?

According to the REN21 Renewables Global Status Report 2014, China had 91.4 GW of installed wind capacity by the end of 2013, more than any other country in the world, of which 75.5 GW was in ...
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  • 14.6k
7 votes

What is the difference between "hydro" and "tidal/wave"? And what is the difference between "solar (heat)" and "solar panels"?

Beware that chart - it is from 2004, and hence is very out of date! In particular, photovoltaics ("solar panels") have become cheaper much faster than anybody expected a decade ago, and wave and tidal ...
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  • 3,601
7 votes
Accepted

Energy saving lamps suggestion

The wattage given on the fixture refers to the maximum that can safely be used. That will be dictated by two things: The internal wiring of the fixture, and the heat that it can tolerate. In reality ...
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  • 3,601
7 votes
Accepted

Which is more energy efficient, a washing machine express wash, or normal?

I think a "general principle" is that "express wash" usually means one or more of the following reduce the wash cycle reduce the spin cycle skip a rinse cycle (e.g. by not using any softener) etc. ...
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  • 5,903
7 votes

Electrical usage data logging with wireless data transfer

It sounds like the Kill A Watt wireless might be what you are after. For more alternatives keep reading. There is another product line called the Watts-Up that has USB connections to computers on ...
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7 votes

How much energy do wall outlets with USB waste when not actively charging?

In most countries, legislation limits the amount of power a device on standby, i.e. under power but not performing a function, are allowed to use. In Europe it's 0.5 Watts (see EC Regulation No. 1275/...
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  • 161
6 votes

How can I manage my fridge's contents better?

My solution is meal planning. I found there were three reasons I was throwing food away: it was leftovers that I didn't get around to eating because I had made a meal when there were already ...
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  • 1,777
6 votes

Anything similar to GravityLight that can be readily purchased?

The big advantage of GravityLight is that you can pull the weight once and then you have electricity for a relatively long period (I read somewhere it's 30 minutes). This is ideal when you need to ...
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  • 14k
6 votes
Accepted

How much, if any, does resolution effect the net power consumption of watching online video?

The Natural Resources Defense Council commissioned a study in late 2015 to understand the energy consumption from 4K TVs, titled The Big Picture: Ultra High-Definition Televisions Could Add $1 Billion ...
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  • 11.2k
6 votes

Any way for microinverter PV array to power a house when the grid is down?

tl;dr: Because of how the grid and your inverters work, it's unlikely that there is a solution for your current system. You will either need to set up a communication network with your microinverters ...
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  • 11.2k
6 votes

For electricity use, which is better: Turning all appliances on at the same time, or spread out?

The primary issue being described is Peak Demand charge. The description in LShaver's answer explains a lot of that, but there are a few more pieces that I think are important: Why does peak demand ...
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